Conventionally, beverage dispensing systems have required electrical or gasoline power. Therefore, these systems tend to be bulky and usually are unsuitable for portable applications.
Typically, conventional beverage dispensing systems comprise a high pressure carbonator tank plumbed to a carbon dioxide (CO.sub.2) cylinder through a pressure regulator in which the pressure to be supplied to the carbonator tank is reduced to approximately 90 pounds per square inch (psi). A motorized pump plumbed to a fixed water tap system is used to pressurize the water supplied to the tank to approximately 200 psi. The high pressure water flows into the carbonator tank, overcoming the rising pressure of the CO.sub.2 gas contained therein. As the carbonator tank fills with this high pressure water, a pocket of CO.sub.2 gas that exists above the water is compressed, forcing the CO.sub.2 gas to be absorbed into the water, thereby creating carbonated water. In that these conventional beverage dispensing systems require a constant source of power to operate the pump motor, use of such systems is generally limited to fixed installations.
Although portable beverage dispensing systems that do not require electrical or gasoline powered pumps have been developed, these systems have several disadvantages. One such system is that disclosed in U.S. Pat. No. 5,411,179 (Oyler et al.) and U.S. Pat. No. 5,553,749 (Oyler et al.). Similar to the systems described in the present disclosure, the system described in these patents use high pressure CO.sub.2 gas supplied by a CO.sub.2 tank to pressurize the water that is supplied to a carbonator tank. Unlike the present systems described in the present disclosure, however, the system described in these patent references use a low pressure carbonator which typically operates at pressures below 100 psi.
Despite providing for some degree of water carbonation (typically, approximately 2.5%), such low pressure systems do not produce beverages having a commercially acceptable level of carbonation (generally between 3% to 4%). Experimentation has shown that the pressurized water must be cooled to a low temperature prior to entering the carbonator tank of these systems to achieve absorption of CO.sub.2 gas into the water. This cooling typically is effected by using a cold plate through which the pressurized water passes just prior to being supplied to the carbonator tank.
As mentioned above, low, albeit marginally acceptable, levels of carbonation can be attained with these low pressure systems. One significant drawback of using this method, however, is that the CO.sub.2 gas contained within the carbonated water can be quickly diffused from the water when it is heated to a warmer temperature. Accordingly, when the carbonated water is post-mixed with relatively warm liquids such as concentrated syrups, juices, and the like, the relatively small amount of carbonation contained within the water can be quickly lost.
From the foregoing, it can be appreciated that it would be desirable to have a self-contained beverage dispensing system that is completely portable and that produces beverages having a commercially acceptable level of stable carbonation.